Korean Potato Salad

Step 1

Place1 small red onion, finely chopped,2 Persian cucumbers, halved lengthwise, thinly sliced crosswise,1 small carrot, peeled, quartered lengthwise, thinly sliced crosswise, and1 tsp. Diamond Crystal or ½ tsp. Morton kosher saltin medium bowl and massage until vegetables look shiny and are just starting to release some liquid. Let sit while potatoes cook to allow vegetables to soften further and release more liquid (at least 15 minutes).

Step 2

Place1 lb. russet potatoes (about 2 medium), peeled, cut into eight equal pieces, in medium saucepan and pour in cold water to cover by 2". Season generously with salt and bring to a simmer over medium-high heat. Carefully lower2 large eggs, rinsed, into pan. If using1 cup fresh corn kernels (from about 1 ear), add to pot. Cover and cook, adjusting heat as needed to maintain a simmer, 10 minutes (exactly). Using a slotted spoon, transfer eggs to a bowl of ice water. Slide a skewer into a potato piece; there should be no resistance. If potatoes aren’t tender, continue cooking until they are, up to 5 minutes longer. Drain cooked potatoes and corn (if using) in a fine-mesh sieve; return to pot.

Step 3

Peel eggs and add to pot with potatoes. Using a potato masher or fork, smash eggs and potatoes until broken up into small, irregular pieces (exact size doesn’t matter).

Step 4

Drain vegetables in same sieve, squeezing fistfuls very hard to remove excess liquid. Add to potato mixture along with½ cup mayonnaise,2 Tbsp. unseasoned rice vinegar or distilled white vinegar,1 Tbsp. plus 1 tsp. sugar,1 tsp. yellow mustard (such as French’s), and1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt; mix well with a rubber spatula to combine (potatoes will break up further and become creamy). Taste and season with more salt if needed. Transfer potato salad to an airtight container, cover, and refrigerate until cold, at least 1 hour, before serving.

Do Ahead:Salad can be made 2 days ahead. Keep chilled.